Replace system block with thread progress block

The ERTS internal system block functionality has been replaced by
new functionality for blocking the system. The old system block
functionality had contention issues and complexity issues. The
new functionality piggy-backs on thread progress tracking functionality
needed by newly introduced lock-free synchronization in the runtime
system. When the functionality for blocking the system isn't used
there is more or less no overhead at all. This since the functionality
for tracking thread progress is there and needed anyway.

5 files changed, 28 insertions, 35 deletions

diff --git a/erts/emulator/sys/common/erl_check_io.c b/erts/emulator/sys/common/erl_check_io.c
index 6d4ad459cc..ba88fd1d39 100644
--- a/erts/emulator/sys/common/erl_check_io.c
+++ b/erts/emulator/sys/common/erl_check_io.c
@@ -35,6 +35,7 @@
 #include "sys.h"
 #include "global.h"
 #include "erl_check_io.h"
+#include "erl_thr_progress.h"
 
 #ifdef ERTS_SYS_CONTINOUS_FD_NUMBERS
 #  define ERTS_DRV_EV_STATE_EXTRA_SIZE 128
@@ -1164,7 +1165,6 @@ ERTS_CIO_EXPORT(erts_check_io)(int do_wait)
 #ifdef ERTS_ENABLE_LOCK_CHECK
     erts_lc_check_exact(NULL, 0); /* No locks should be locked */
 #endif
-    erts_smp_activity_begin(ERTS_ACTIVITY_WAIT, NULL, NULL, NULL);
     pollres_len = sizeof(pollres)/sizeof(ErtsPollResFd);
 
     erts_smp_atomic_set_nob(&pollset.in_poll_wait, 1);
@@ -1174,7 +1174,6 @@ ERTS_CIO_EXPORT(erts_check_io)(int do_wait)
 #ifdef ERTS_ENABLE_LOCK_CHECK
     erts_lc_check_exact(NULL, 0); /* No locks should be locked */
 #endif
-    erts_smp_activity_end(ERTS_ACTIVITY_WAIT, NULL, NULL, NULL);
 
     erts_deliver_time(); /* sync the machine's idea of time */
 
@@ -1881,13 +1880,12 @@ ERTS_CIO_EXPORT(erts_check_io_debug)(void)
 
     erts_printf("--- fds in pollset --------------------------------------\n");
 
-#ifdef ERTS_SMP
-# ifdef ERTS_ENABLE_LOCK_CHECK
+#if defined(ERTS_SMP) && defined(ERTS_ENABLE_LOCK_CHECK)
     erts_lc_check_exact(NULL, 0); /* No locks should be locked */
-# endif
-    erts_block_system(0); /* stop the world to avoid messy locking */
 #endif
 
+    erts_smp_thr_progress_block(); /* stop the world to avoid messy locking */
+
 #ifdef ERTS_SYS_CONTINOUS_FD_NUMBERS
     counters.epep = erts_alloc(ERTS_ALC_T_TMP, sizeof(ErtsPollEvents)*max_fds);
     ERTS_POLL_EXPORT(erts_poll_get_selected_events)(pollset.ps, counters.epep, max_fds);
@@ -1909,9 +1907,7 @@ ERTS_CIO_EXPORT(erts_check_io_debug)(void)
     safe_hash_for_each(&drv_ev_state_tab, &doit_erts_check_io_debug, (void *) &counters);
 #endif
 
-#ifdef ERTS_SMP
-    erts_release_system();
-#endif
+    erts_smp_thr_progress_unblock();
 
     erts_printf("\n");
     erts_printf("used fds=%d\n", counters.used_fds);
diff --git a/erts/emulator/sys/common/erl_mseg.c b/erts/emulator/sys/common/erl_mseg.c
index 3a90db607b..49750ff6ce 100644
--- a/erts/emulator/sys/common/erl_mseg.c
+++ b/erts/emulator/sys/common/erl_mseg.c
@@ -38,6 +38,7 @@
 #include "erl_time.h"
 #include "erl_alloc.h"
 #include "big.h"
+#include "erl_thr_progress.h"
 
 #if HAVE_ERTS_MSEG
 
@@ -450,14 +451,12 @@ mseg_recreate(ErtsMsegAllctr_t *ma, MemKind* mk, void *old_seg, Uint old_size, U
 do {									\
     if ((MA)->is_thread_safe)						\
 	ERTS_LC_ASSERT(erts_lc_mtx_is_locked(&(MA)->mtx)		\
-		       || erts_smp_is_system_blocked(0)			\
-		       || (ERTS_IS_CRASH_DUMPING			\
-			   && erts_smp_is_system_blocked(ERTS_BS_FLG_ALLOW_GC)));\
+		       || erts_smp_thr_progress_is_blocking()		\
+		       || ERTS_IS_CRASH_DUMPING);			\
     else								\
 	ERTS_LC_ASSERT((MA)->ix == (int) erts_get_scheduler_id()	\
-		       || erts_smp_is_system_blocked(0)			\
-		       || (ERTS_IS_CRASH_DUMPING			\
-			   && erts_smp_is_system_blocked(ERTS_BS_FLG_ALLOW_GC)));\
+		       || erts_smp_thr_progress_is_blocking()		\
+		       || ERTS_IS_CRASH_DUMPING);			\
 } while (0)
 #define ERTS_DBG_MK_CHK_THR_ACCESS(MK) \
   ERTS_DBG_MA_CHK_THR_ACCESS((MK)->ma)
diff --git a/erts/emulator/sys/unix/sys.c b/erts/emulator/sys/unix/sys.c
index 15e110a6cc..8e8d4cce61 100644
--- a/erts/emulator/sys/unix/sys.c
+++ b/erts/emulator/sys/unix/sys.c
@@ -52,6 +52,7 @@
 #define ERTS_WANT_GOT_SIGUSR1
 #define WANT_NONBLOCKING    /* must define this to pull in defs from sys.h */
 #include "sys.h"
+#include "erl_thr_progress.h"
 
 #if defined(__APPLE__) && defined(__MACH__) && !defined(__DARWIN__)
 #define __DARWIN__ 1
@@ -2425,11 +2426,7 @@ void erts_do_break_handling(void)
      * therefore, make sure that all threads but this one are blocked before
      * proceeding!
      */
-    erts_smp_block_system(0);
-    /*
-     * NOTE: since we allow gc we are not allowed to lock
-     *       (any) process main locks while blocking system...
-     */
+    erts_smp_thr_progress_block();
 
     /* during break we revert to initial settings */
     /* this is done differently for oldshell */
@@ -2457,7 +2454,7 @@ void erts_do_break_handling(void)
       tcsetattr(0,TCSANOW,&temp_mode);
     }
 
-    erts_smp_release_system();
+    erts_smp_thr_progress_unblock();
 }
 
 /* Fills in the systems representation of the jam/beam process identifier.
@@ -2868,7 +2865,7 @@ erl_sys_schedule(int runnable)
 {
 #ifdef ERTS_SMP
     ERTS_CHK_IO(!runnable);
-    ERTS_SMP_LC_ASSERT(!ERTS_LC_IS_BLOCKING);
+    ERTS_SMP_LC_ASSERT(!erts_thr_progress_is_blocking());
 #else
     if (runnable) {
 	ERTS_CHK_IO(0);		/* Poll for I/O */
@@ -2937,15 +2934,15 @@ signal_dispatcher_thread_func(void *unused)
 	     *         to other threads.
 	     *
 	     * NOTE 2: The signal dispatcher thread is not a blockable
-	     *         thread (i.e., it hasn't called 
-	     *         erts_register_blockable_thread()). This is
-	     *         intentional. We want to be able to interrupt
-	     *         writing of a crash dump by hitting C-c twice.
-	     *         Since it isn't a blockable thread it is important
-	     *         that it doesn't change the state of any data that
-	     *         a blocking thread expects to have exclusive access
-	     *         to (unless the signal dispatcher itself explicitly
-	     *         is blocking all blockable threads).
+	     *         thread (i.e., not a thread managed by the
+	     *         erl_thr_progress module). This is intentional.
+	     *         We want to be able to interrupt writing of a crash
+	     *         dump by hitting C-c twice. Since it isn't a
+	     *         blockable thread it is important that it doesn't
+	     *         change the state of any data that a blocking thread
+	     *         expects to have exclusive access to (unless the
+	     *         signal dispatcher itself explicitly is blocking all
+	     *         blockable threads).
 	     */
 	    switch (buf[i]) {
 	    case 0: /* Emulator initialized */
@@ -2985,7 +2982,7 @@ signal_dispatcher_thread_func(void *unused)
 			 buf[i]);
 	    }
 	}
-	ERTS_SMP_LC_ASSERT(!ERTS_LC_IS_BLOCKING);
+	ERTS_SMP_LC_ASSERT(!erts_thr_progress_is_blocking());
     }
     return NULL;
 }
diff --git a/erts/emulator/sys/win32/sys.c b/erts/emulator/sys/win32/sys.c
index a6b1606dd8..ace1e1fca0 100644
--- a/erts/emulator/sys/win32/sys.c
+++ b/erts/emulator/sys/win32/sys.c
@@ -3384,7 +3384,7 @@ erl_sys_schedule(int runnable)
 {
 #ifdef ERTS_SMP
     erts_check_io(!runnable);
-    ERTS_SMP_LC_ASSERT(!ERTS_LC_IS_BLOCKING);
+    ERTS_SMP_LC_ASSERT(!erts_thr_progress_is_blocking());
 #else
     if (runnable) {
 	erts_check_io(0);	/* Poll for I/O */
diff --git a/erts/emulator/sys/win32/sys_interrupt.c b/erts/emulator/sys/win32/sys_interrupt.c
index 1d73edd30b..93aaa23f97 100644
--- a/erts/emulator/sys/win32/sys_interrupt.c
+++ b/erts/emulator/sys/win32/sys_interrupt.c
@@ -21,6 +21,7 @@
  */
 #include "sys.h"
 #include "erl_alloc.h"
+#include "erl_thr_progress.h"
 #include "erl_driver.h"
 #include "../../drivers/win32/win_con.h"
 
@@ -52,14 +53,14 @@ void erts_do_break_handling(void)
      * therefore, make sure that all threads but this one are blocked before
      * proceeding!
      */
-    erts_smp_block_system(0);
+    erts_smp_thr_progress_block();
     /* call the break handling function, reset the flag */
     do_break();
 
     ResetEvent(erts_sys_break_event);
     ERTS_UNSET_BREAK_REQUESTED;
 
-    erts_smp_release_system();
+    erts_smp_thr_progress_unblock();
 }